Hybrid system for vehicle with 4WD start mode

A hybrid system for a vehicle having a first set of road wheels and a second set of road wheels, comprising:

• first controller means for receiving a torque request for an engine driving torque (vTRQe) and combining an idle speed torque and the engine driving torque (vTRQe) to generate an engine torque command signal;
• an engine drivingly coupled with the first set of road wheels to apply a first driving torque to the first set of road wheels in response to the engine torque command signal;
• second controller means, in communication with the first controller means, for generating the torque request and a motor torque command signal taking into account a creep torque portion (CREEP_TRQ) of the first driving torque applied to the first set of road wheels and a desired driving torque (tTRQ1) during starting the vehicle from standstill;
• and
• a motor drivingly coupled with the second set of road wheels to apply a second driving torque to the second set of road wheels in response to the motor torque command signal.

A method for controlling a vehicle having a first set of road wheels, a second set of road wheels and a drivetrain, the drivetrain including an engine drivingly coupled with the first set of road wheels to apply a first driving torque to the first set of road wheels in response to an engine torque command signal, and a motor drivingly coupled with the second set of road wheels to apply a second driving torque to the second set of road wheels in response to a motor torque command signal, the control method comprising:

• determining a desired driving torque (tTRQ1);
• determining a creep torque portion (CREEP_TRQ) of the first driving torque applied to the first set of road wheels;
• comparing the desired driving torque (tTRQ1) to a threshold established based on the creep torque portion (CREEP_TRQ);
• subtracting the creep torque portion (CREEP_TRQ) from the desired driving torque (tTRQ1) to give a modified desired driving torque (tTRQ2);
• setting the modified desired driving torque (tTRQ2) as an intermediate motor driving torque (vFTRQint) when the desired driving torque (tTRQ1) is not greater than the threshold;
• setting a predetermined percentage of the desired driving torque (tTRQ1) as the intermediate motor driving torque (vFTRQint) when the desired driving torque (tTRQ1) exceeds the threshold;
• reducing the intermediate motor driving torque (vFTRQint) toward zero to give a motor driving torque (vFTRQ) upon a predetermined condition being fulfilled after starting the vehicle;
• subtracting the motor driving torque (vFTRQ) from the modified desired engine torque (tTRQ2) to give an engine/motor driving torque (vRTRQ);
• determining the motor torque command signal in response to the motor driving torque (vFTRQ);
• and
• determining the engine torque command signal in response to the engine/motor driving torque (vRTRQ).

A computer readable storage medium having stored therein data representing instructions executable by a computer to control a vehicle having a first set of road wheels, a second set of road wheels and a drivetrain, the drivetrain including an engine drivingly coupled with the first set of road wheels to apply a first driving torque to the first set of road wheels in response to an engine torque command signal, and a motor drivingly coupled with the second set of road wheels, the computer readable storage medium comprising:

• instructions for determining a creep torque portion (CREEP_TRQ) of the first driving torque applied to the first set of road wheels;
• instructions for generating a torque request for an engine driving torque (vRTRQe) and a motor torque command signal taking into account the determined creep torque portion (CREEP_TRQ) and a desired driving torque (tTRQ1) during starting the vehicle from standstill;
• and
• instructions for applying the motor torque command signal to the motor, causing the motor to apply a second driving torque to the second set of road wheels.